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Why does color of substances not disappear after some time?

If you are seriously interested in understanding why things are colored, there is a book called The Physics and Chemistry of Color: The Fifteen Causes of Color, by Kurt Nassau. It should be available ...
AChem's user avatar
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8 votes
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Are there pigments that will only show their colour after applying water?

First, do you definitely mean "pigment", rather than "stain" or "dye"? Second, there are many dyes, stains and pigments that change color when dampened. The do so in a ...
DrMoishe Pippik's user avatar
6 votes

Why hot iron turns from red to white and then blue?

White is not a color. It is the signal sent by the eye to the brain when the light contains the same proportion of red, orange, yellow, green, blue and violet as in the sun light. If the light ...
Maurice's user avatar
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6 votes
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Can a colorant be mixed into zirconia powder?

Setting aside commercial sources whose manufacturers are unlikely to reveal their secrets, Chen et al.[1] describe the coloration of zirconia with oxides of cerium(IV), iron(III), and bismuth(III): ...
Oscar Lanzi's user avatar
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6 votes

Changes of colour of sunset yellow in water

Pictures might have helped. The sunset yellow FCF molecule is actually a disodium disulfonate with an additional phenolic hydroxyl group and a diazo function, with overall formula $\ce{C_{16}H_{10}...
Oscar Lanzi's user avatar
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6 votes

Why does color of substances not disappear after some time?

Absorption and transmission do play a role in the color of the compound and absorption of a certain region of the visible light results in transmission of the remainder of the region, often resulting ...
ananta's user avatar
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3 votes

Azo dyes with different colours than Yellow, Orange and Red

Wikipedia article Category:Azo dyes list you all the azo dyes in the whole color spectrum, with colors explicitly indicated (yellow, orange, brown, red, blue, black) in the names of some of the dyes. ...
Nilay Ghosh's user avatar
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2 votes
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Reason behind paramagnetic substances having color

As pointed out in the comments, this is not a good generalization. You correctly stated that paramagnetic complexes have (at least) one unpaired electron, while diamagnetic ones have a closed shell. ...
user137746's user avatar
2 votes

How can I make a black precipitate without a sulfide?

Disclaimer This answer is somewhat an addition to the existing ones. Here, I will try to present a practically feasible method for obtaining lead(IV) oxide $\ce{PbO2}$ from the available reagents. It ...
Exeplone's user avatar
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2 votes

Why Green Solution After Putting Bismuth Antimony in Nitrogen Acid

Copper could have come from the sample. From Belmont Metals: Bismuth as an alloying element can be used in the production of fusible alloys ( low melting point alloys ) and Bismuth based low ...
Oscar Lanzi's user avatar
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2 votes
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Azo dyes with different colours than Yellow, Orange and Red

More complex azo dyes can be other colors, as with trypan blue. With its more complex structure comes more extended conjugation, which shifts visible light absorption from the shorter violet and blue ...
Oscar Lanzi's user avatar
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1 vote

Finding the pH level of a liquid process

AFAIK, the universal indicator already contains bromthymol blue. Why to add it explicitly? RGB value is not enough to determine pH due multiple factors. Aside of that, such a measurement is useless, ...
Poutnik's user avatar
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1 vote

Changes of colour of sunset yellow in water

Powders are often paler than large crystals of the same substance, or of the substance in solution, because of diffraction, interference and quantum interactions of light with small particles. Some ...
DrMoishe Pippik's user avatar
1 vote

What substances are typically used to produce cyan, magenta, and yellow ink?

If you are interested in the colour pigments, there is a lot of similar ones. And the different mixtures can be made with almost no difference. You can find a lot of different options for CMYK (...
XuMuK's user avatar
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1 vote

Colour of CuO and CuCl2

$\ce{[CuCl4]^2-(aq)}$ is even yellow. $\ce{Cl-}$ ligands attached to $\ce{Cu^2+}$ shift color toward green and yellow. Solids are special. They may follow color of solutions, if structure is not far ...
Poutnik's user avatar
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1 vote

Explanation for why nickel turns green in hydrochloric acid

This question does look ambiguous. The question states that Nickel is added to aqueous Hydrochloric acid. The word aqueous might suggest that the complex that the present in the solution is [Ni(H2O)6]...
DarkKnight's user avatar
1 vote

Why is nitrogen dioxide brown?

To understand this, we must take a look at these molecules one by one. Nitrogen Dioxide[NO2]: This here is its resonance structure/canonical structure. NO2 is a molecule in which a Nitrogen is ...
Anjankumar's user avatar
1 vote

Bleach turned towel bright pink before fading to white

Possible sunscreen was on the towels? Sunscreen will do that when bleach is added.
Casey Sue's user avatar

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